The present disclosure relates to a gas turbine engine and, more particularly, to cooling structure used with a combustor section.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
The combustor section typically includes an outer support shell lined with heat shields, often referred to as floatwall liner panels, which are attached to the outer shell with studs and nuts. In certain arrangements, each dilution passage is located through the liner panels and support shell to direct dilution air into the combustion chamber. In addition to the dilution passages, the outer shell may also have relatively smaller air impingement passages to direct cooling air between the liner panels and the support shell to impinge upon the cold side of the liner panels. This cooling air then exits effusion passages through the liner panels to form a cooling air film on a hot side of the floatwall panels that serves as a barrier to minimize thermal damage.
One particular region where localized combustor hot spots may arise is around the dilution passages. The dilution passages inject relative lower temperature air into the swirling fuel-rich cross flow for combustion. As the air penetrates into the fuel-rich cross-stream, heat release takes place along the reaction front to form high temperature regions around the dilution passages. A stagnation region along the upstream side of the dilution passages may also form a higher pressure environment such that cross flow momentum deflects the incoming dilution air jet. The combination of high pressure and the deflection of the incoming dilution air jet may form a high temperature recirculation region along the inner surface of the dilution passage.
A lower velocity region of flow along the perimeter of the dilution passage may also be highly susceptible to inflow of hot combustion gas products. The inflow of these products can occur within a localized ingestion region and may result in a durability concern because a low temperature boundary condition is replaced by high temperature gases.